The present invention relates to a coating method which achieves thin-layer coating on a web and a coating apparatus therefore.
Heretofore, as a method of coating a coating liquid onto a web, U.S. Pat. No. 4,457,256 is known. This method is to conduct coating and improve wettability for reducing the layer thickness at high speed after providing voltage applying processing with the web which is subjected to dielectric polarizing. However, according to this method, when the coating liquid is coated on aforesaid web subjected to aforesaid dielectric polarization, the direction of polarization becomes diversified due to influence by the coating liquid, resulting in uneven coating. In addition, there was also a problem that coating speed could not be increased.
Further, in TOKUKAIHEI No. 2-293072, TOKUKAIHEI No. 2-293071, TOKUKAIHEI No. 3-501702 and TOKUGANSHO No. 61-146369, a method to conduct coating while a web is applied with a voltage. However, with such a method, uneven charging takes place, result in uneven coating.